Enhanced acid stability and bioaccessibility of curcumin-loaded nanodispersions prepared with shellac, gum arabic,...

Shellac is a potential encapsulating material for lipophilic polyphenols like curcumin. However, shellac nanocapsules aggregate and precipitate at acidic pH. In this study, gum arabic (2.0 % w/v) was used with different concentrations of Tween 20 to stabilize shellac nanocapsules containing 5.0 mg/mL of curcumin, prepared using the pH-cycle method, at acidic pH. Gum arabic alone stabilized shellac nanocapsules and reduced curcumin encapsulation efficiency. With additional 0.8 % w/v Tween 20, both acidic stability of dispersions and curcumin encapsulation efficiency of >60 % were achieved at pH 7.0, 4.5, and 3.0. Furthermore, the nanocapsules demonstrated physical and chemical stability during 28-day storage at 4 °C. Nanoencapsulation significantly improved the antioxidant activity of curcumin compared to its free form and resulted in a bioaccessibility of over 50 % for all nanodispersions. This study is significant for the effective delivery of lipophilic bioactive compounds in different functional foods and beverages.